21259730 has 16 divisors (see below), whose sum is σ = 39201624. Its totient is φ = 8296320.

The previous prime is 21259729. The next prime is 21259739. The reversal of 21259730 is 3795212.

It can be written as a sum of positive squares in 4 ways, for example, as 17530969 + 3728761 = 4187^2 + 1931^2 .

It is a super-2 number, since 2×21259730² = 903952239345800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21259693 and 21259702.

It is not an unprimeable number, because it can be changed into a prime (21259739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25517 + ... + 26336.

Almost surely, 2^21259730 is an apocalyptic number.

21259730 is a deficient number, since it is larger than the sum of its proper divisors (17941894).

21259730 is a wasteful number, since it uses less digits than its factorization.

21259730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51901.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21259730 is about 4610.8274745429. The cubic root of 21259730 is about 277.0251815830.

The spelling of 21259730 in words is "twenty-one million, two hundred fifty-nine thousand, seven hundred thirty".